Heretofore, large pressurized filtering vessels, and other vessels for containing pressurized media, have typically employed eye bolt lid attachment systems. Such conventional systems include a plurality of bolt fasteners pivotally mounted to the rim of the vessel housing at spaced intervals. The number and spacing of the fasteners is usually a function of the pressure rating for the vessel. When the lid is placed onto the housing, the bolts are pivoted upwardly into corresponding U-shaped brackets formed around the periphery of the lid. A nut is screwed onto the exposed shank portion of each bolt fastener and against the bracket to hold secure the lid to the housing. This fastening method is tedious and time consuming. Furthermore, it is known that substantially uniform clamping pressure about the circumference of the lid is desirable. Thus, the torque applied to each nut must be checked to assure that uniform clamping pressure is applied between the lid and the housing.
Other conventional lid attachment systems employ a variety of specially formed lid perimeters and housing lock rings which cooperatively engage to secure the lid to the housing when the lid is rotated relative to the housing. Some of these quick close configurations include, for example, a plurality of downwardly projecting tabs with upturned outer ends inset from the outer edge of the lid which, when the lid is rotated, engage a plurality of cam surfaces formed into slots in the side wall of the housing. Other quick close configurations employ a plurality of spaced lugs which extend outwardly from the side edge of the lid, and a plurality of similarly spaced cams which extend inwardly from a lock ring attached to the top of the housing side wall. When the lid is rotated within the lock ring, the lugs coact with the internal cams to secure the lid to the vessel housing. These systems, however, require precision machining of the vessel housing and lid to ensure an adequate seal. Thus, such conventional systems are generally expensive and difficult to manufacture and assemble.